This invention relates to a high-frequency amplifier device which amplifies or frequency-converts a feeble electric wave received by an antenna or the like.
FIG. 1 is a setup diagram showing an example of a prior-art high-frequency amplifier device, while FIG. 2 is a sectional view showing an example of the practicable structure of the high-frequency amplifier device having the setup in FIG. 1. In the figures, numeral 1 designates a high-frequency amplifier portion, numeral 4 the signal output terminal of the amplifier device, and numeral 7 the case of the amplifier device. Numeral 71 indicates the input flange of the amplifier device, numeral 72 the input portion thereof for a high-frequency signal, which is formed of a waveguide, numeral 73 the detector portion thereof which detects the high-frequency signal transmitted and applied by the waveguide, and numeral 74 the irreversible circuit thereof which is represented by an isolator. The high-frequency amplifier portion 1 has the function of frequency conversion partly or wholly, and the function of high-frequency will be explained as a typical example hereinbelow.
Next, the operation of the prior-art device will be described. The high-frequency signal received by the waveguide input portion 72 is detected by the detector portion 73, and the detected signal is sent to an isolator or the like irreversible element 74 as a coaxial mode or a strip line mode. The irreversible element 74 transmits the signal with a low loss in the direction of arrows as indicated in the figures, whereas it operates to afford a large attenuation to a signal in the reverse direction. Now that the input signal is transmitted in the direction of the illustrated arrows, it is transmitted to the high-frequency amplifier portion 1 with only a low loss. After the input signal is amplified to a required level in the high-frequency amplifier portion 1, it is delivered out from the signal output terminal 4. The high-frequency amplifier portion 1 is so constructed that a plurality of semiconductor amplifier elements are arranged at suitable intervals on a strip line which is made of a dielectric exhibiting low loss characteristics to high frequencies, for example, ceramics or teflon, and that resistors and capacitors for supplying D.C. biases to the semiconductor amplifier elements are added. Bipolar transistors, field-effect transistors, etc. are extensively used as the semiconductor amplifier elements for amplifying the high frequencies. The irreversible element 74 is used for improving the input impedance of the high-frequency amplifier portion 1, or for preventing the high-frequency amplifier portion 1 from causing oscillations etc., under the influence of an oscillator impedance on the input side. When viewed laterally, the waveguide input portion 72 has a shape as shown in FIG. 3. The section of the waveguide input portion 72 is oblong, and the detector portion 73 protrudes into the waveguide input portion 72 as shown in FIG. 2, by way of example. The detector portion 73 detects the input of an electric field in the direction of an arrow indicated in FIG. 3, and sends it to the high-frequency amplifier portion 1.
Since the prior-art high-frequency amplifier device is constructed as described above, it can amplify only the input of the electric field in the direction of the arrow indicated in FIG. 3. Broadcast satellites in recent years often send signals by the use of two orthogonal polarized waves. The prior-art high-frequency amplifier device as shown in FIGS. 1 thru 3 has had the problem that, in order to amplify an input signal of an electric field perpendicular to the arrow, the input flange 71 of the high-frequency amplifier device needs to be detached and then remounted with a rotational angle of 90.degree.. Alternatively, an antenna for receiving the input signals from the satellite needs to be switched so as to receive the perpendicular polarized wave, and to transmit the received wave to the high-frequency amplifier device.